The present invention relates to continuously variable transmissions.
One type of known continuously variable transmission is accomplished by varying the lateral spacing between a pair of opposing sheaves forming a pulley. The belt driven between the sheaves varies in position and lineal speed according to radial spacing from the center of the pulley.
In another known approach, a fluid or hydraulic pump drives a hydraulic motor, and the pump stroke is varied to change the amount of hydraulic fluid delivered to the motor, to provide continuously variable displacement of the latter. Various means are known for providing a variable displacement pump with a variable pump stroke, for example swash plates and the like.
There is a need for a continuously variable transmission which can be constructed using a constant displacement pump, rather than a variable displacement pump and its attendant complexity and cost.
The present invention addresses and solves this need. In preferred form, a fluid motor is driven by a constant displacement pump of fixed fluid power stroke, and means are provided for varying the output stroke of the fluid driven motor without varying the power stroke of the pump.